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Three-dimensional (3D) flower-like cubic Ni 3 S 4 nanoplates with single crystalline nature were successfully prepared through decomposing bis(thiourea) nickel(II) chloride crystals (BTNC). The samples were characterized by X-ray diffraction, scanning electron microscope, transmission electron microscope, selected area electron diffraction and Raman spectroscopy. Results show that the as-prepared products are pure cubic Ni 3 S 4 and stable in range of 180-220 • C with single crystal nature providing high surface areas, and higher reaction temperature leads to lower surface areas. Typical Raman peaks of the as-synthesized 3D flower-like cubic Ni 3 S 4 at 200 • C are located at 239, 286, 337, 379, 423, 478 and 630 cm −1. Magnetization measurement indicates that single crystalline Ni 3 S 4 nanoplates prepared at 200 • C displays antiferromagnetic behaviour.

The structure, electronic and elastic properties of CrO 2 in the high pressure orthorhombic CaCl 2 (Pnnm) phase are investigated by first-principles calculations based on density functional theory (DFT). Our calculated crystal parameters are in good agreement with the available experimental data. The electronic band structure, density of state (DOS) and projected density of state (PDOS) at 14 GPa are studied within local spin density approximation (LSDA) and generalized gradient approximation (GGA) in details. The CaCl 2 phase of CrO 2 still has the half metal character, which is in accordance with previous theoretical predictions. The elastic constants, bulk modulus, shear modulus, Young's modulus and Poisson ratio under pressures are successfully obtained for the orthorhombic CaCl 2 phase of CrO 2. This structure is mechanically stable at our applied range of pressures. The calculated elastic anisotropic factors show that the CaCl 2 phase of CrO 2 is provided with high elastic anisotropy and the elastic anisotropy decreases with increasing pressures. The propagation speed of transverse, longitudinal elastic wave together with associated Debye temperatures are also estimated.

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The structural, elastic and thermodynamic properties of [Formula: see text] in the [Formula: see text] structure under pressure have been investigated using ab initio plane wave pseudopotential method within the generalized gradient approximation. The calculated structural parameters and equation of state are in excellent agreement with the available experimental and theoretical results. The elastic constants of [Formula: see text] at ambient condition are calculated, and the bulk modulus obtained from these calculated elastic constants agrees well with the experimental data. The pressure dependence of the elastic constants, bulk modulus, shear modulus and Young’s modulus has also been investigated. The Debye temperature presents a slight increase with pressure. [Formula: see text] exhibits ductibility and low hardness characteristics, the ductibility increases while the hardness decreases with the increasing of pressure. The pressure effect on the heat capacity and thermal expansion coefficient for [Formula: see text] is much larger.

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